Alkali-aggregate reactions in concrete pose a major problem that reduces the durability and working life of construction objects, especially those exposed a great deal of moisture and high temperatures. This paper analyzes the causes and consequences of chemical reactions in concrete that lead to this phenomenon, considering the types of aggregates used, cement types, additives as well as environmental conditions that favor this appearance. In order to prevent this phenomenon, it is necessary to use aggregates containing smaller amount of amorphous silica in the case of an alkali-silica reaction, or a limited amount of aggregates containing carbonates in the case of an alkali-carbonate reaction. It is recommended to use a cement containing small quantities of alkalis, as well as Portland cement with addition of granulated blast furnace slag, silica fume or fly ash, and also reduced humidity in the concrete.
